<select id="select1"name="select1"onchange="tt(id)"><option value="">请选择</option><option value="1">opt1</option>< 展开
<select id="select1"name="select1"onchange="tt(id)"><option value="">请选择</option><option value="1">opt1</option><option value="2">opt2</option><option value="3">opt3</option></select><script>var tt= function(id) { var aa = document.getElementById(id);//alert(aa.value);if(aa.value=='2') document.getElementById('t').innerHTML="hello";else document.getElementById('t').innerHTML='<font color="red">*</font>hello';} </script><p id="t"><font color="red">*</font>hello</p>收起
